OBD / DTC guide
P0300
Random / Multiple Cylinder Misfire Detected
P0300 means the engine controller detected misfire activity across multiple cylinders or randomly across events. Ignition, fuel delivery, intake leaks, and mechanical issues can all be in play. Cylinder-specific codes (P030x) narrow the story when present.
Related symptoms
The same code can show up with different feelings behind the wheel. These links go to general symptom guides—pairing symptoms with context usually beats guessing from the code alone.
Common root-cause themes
Priority changes by vehicle platform. Treat this as orientation, not a workshop verdict—confirm with testing for your car.
- Often discussed pattern
Ignition components (plugs/coils/wires) on gasoline engines.
- Often discussed pattern
Fuel pressure low or injector imbalance.
- Common in some setups
Intake leaks disturbing trims.
- Depends heavily on context
Mechanical compression or timing issues—less common but serious.
Risk and urgency
A flashing MIL with misfire often means high catalyst stress risk—ease off throttle and avoid prolonged high load until diagnosed.
Sensible first checks
- Look for cylinder-specific misfire codes alongside P0300.
- Note fuel level, recent fuel changes, and maintenance history.
- Avoid long cranking or repeated hard pulls if the car feels unsafe.
- Professional isolation tests beat guessing parts.
- Use the guided flow to structure symptom timing.
Related parts (context)
Use these pages for background. A parts swap without confirmation can be expensive if the root cause is elsewhere.
Parts hubInterpret the code with real-world context
In the guided flow, combine the code with how the car feels, when it happens, and any other codes stored alongside it.
P0300 fault code — more context
P0300 is a wide net. Good diagnostics shrink the net using companion codes, fuel trims, and cylinder tests.
This page resists ‘replace everything’ thinking.